CHICKWEED has completely disappeared from my garden, although for years it was the major pest, growing superbly through the winter and bursting forth in spring.

Now, on the other hand, violets have become a royal purple pain. Readers sometimes have complained of violets as weeds, but I always thought they exaggerated. Surely it could be no great trouble to pull out a few volunteer seedlings of the little wild violets?

It is far otherwise. Just as human diseases appear to vary in severity over the decades, for no very good reason that I know, so do weeds vary in virulence in the garden.

I have always had violets, all my life, and I recall that once the Confederate violets that used to seed madly all over the place suddenly died out in the space of two years. Whether they eventually exhaust the soil of some critical ingredient necessary to their health, or whether they fall victim to some undetectable virus, or whether something entirely different afflicts them, I have no idea.

The first warm days of spring this year I have been not less than shocked at the intrusion of violets into irises, peonies and daylilies. The seeds evidently germinated last spring or summer and the tough rootstock evidently built up, unnoticed, for several months.

Now, when you examine and scratch the half-inch or so between iris roots, you see flourishing violet rhizomes the size of Lima beans wedged in, and they are even more amazing in the daylilies, where they have intruded between the fans of leaves, even though the fans are touching.

At this time of year the crimson shoots of peonies, some of them only an inch and a half high, are brittle and succulent. It is a task indeed to work like a surgeon among them, trying to grub out the violets without breaking the peony shoots.

So much for enjoying oneself the first warm days of spring.

A plant of great beauty that you rarely see in town gardens is the sweet-flag, Acorus calamus , with sheaves of soft green foliage like an iris, only striped conspicuously with pale yellow their entire length.

I have grown it both in land and in the pool, and it is much simpler to manage in a pool with about four to seven inches of water over the roots, which are merely planted in good heavy soil (ordinary soil such as roses, irises, etc., grow in) in a bucket or box. In a deep pool, you simply raise the container on bricks or whatever to achieve the proper depth of water.

It never fails to surprise gardeners how early in the year water plants start growing. The acorus starts in February and by mid-March the leaves have appeared above the water surface.

The flowers are odd, not showy or very beautiful, but the roots have a tangerine smell and so -- more feebly -- do the leaves.

Water lilies also start sprouting in February, but never float on the water surface until settled warmish weather is here. I spotted the first flower buds on water lilies on March 26, but I would be surprised if flowers appeared in the pool before the end of May or early June.

Usually the earliest tulips are T. kaufmaniana or its numerous hybrid varieties. This year I noticed them first on March 22. Some of the red hybrids of T. fosteriana opened with me on March 29, though it will be another month before the main spate of tulips flowers.

Every year there are little variations in the blooming dates of flowers, and things that bloom together one year many not even overlap in another year.

The pretty single yellow kerria, which I expect to bloom with the tall bearded irises, usually manages to flaunt its gaudy color with the Kurume azaleas, and they do very little to enhance each other. This year it is threatening to bloom before the azaleas, and five weeks before the irises.

Before the end of March I could see fat little clematis buds on the white 'Henryi,' and this may be the place to say that if a sharp freeze damages the new growth of the large-flowered clematis varieties, no great harm is done. They simply put out new growth later and flower as heavily as if nothing had ever happened to them.

It is not that way with the irises. Some years, in some clumps, there is either no bloom or little, or deformed flower stalks. This is the result of the flower bud emerging above ground, inside the fan of leaves, and of being caught by a late freeze. If the freeze is severe enough, the fan may rot. But sometimes the cold is just enough to damage and abort the flower stalk without visible effect on the plant itself. There have been awful years in which irises bloomed poorly, but I can remember only two or three such years in a half-century. When they come they throw iris fanciers into profound gloom.

I am about to blame sparrows for something they may not have done. My splendid flowering plum, Prunus blireiana , should be showing color by the end of March, but I see no sign of flower buds. I have noticed many sparrows sitting about in it through the winter, rubbing their beaks against the twigs. I do not know certainly that they have eaten the flower buds, but I think so, especially since the winter was so cold that the pool was frozen far more days than usually, and the normal drinking supply was therefore not available.

On the other hand, some of these early flowering or ornamental plums have a bad habit of scarcely flowering at all as they enter old age. This is especially true of the purple-leaf P. pissardii , which blooms nicely as a young tree but not in old age. But my pink flowering plum is just now approaching maturity and is far from old age, so I think it was the sparrows, especially since I can see scars of missing buds on the branches.

One of the important things to do, by the way, is to learn to like sparrows if you live in a neighborhood where there are more than a million of them per acre.